<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>DOM对象转成jQuery对象案例</title>
    <script type="text/javascript" src="../js/jquery-1.4.2.js"></script>
</head>
<body>
<input type="text" value="zhang" id="username" name="username" />
</body>
<script type="text/javascript">
    //dom转化为JQUery对象
    var inputObj = document.getElementById("username");
    alert($(inputObj).val());

</script>
</html>